The present invention relates to a front motorcycle wheel suspension device with a single supporting and wheel steering arm, the said arm being adapted, in order to steer the wheel, to turn about a steering axis orthogonal to that of the said wheel and located substantially in the median longitudinal plane of the motorcycle.
The suspension of a chassis or frame of a vehicle on a driving wheel has been considerably simplified in the type of suspension called henceforth "Mac Pherson suspension" and described for example in U.S. Pat. No. 2,842,230 corresponding to French patent published under No. 1 156 145. In this type of suspension, since then improved, the stub axle of the front wheel is carried by a damping tube connected by a link pivoted on the central portion of the frame and the body of the vehicle rests, from a relatively elevated supporting position, directly upon a helical spring interposed between an abutment shoulder of the shock-absorber tube and a bearing plate of the body.
This type of front suspension device has been proposed for motorcycles that require a front wheel support which is accurately centered in the plane of symmetry of the wheel, contrary to four-wheeled vehicles in which a cantilevered mounting of the wheel can easily be accepted. In the solution proposed, the single suspension front arm is connected at its upper end to a suspension and/or shock-absorber block interposed between this end and a front peak of the motorcycle chassis and comprises a bent portion which surrounds a part of the cross-section of the periphery of the wheel and a lower part carrying the wheel axle and provided with a ball-and-socket pivoting piece the pivoting center of which is substantially aligned with the steering axis and which cooperates with the end of a connecting arm rotationally mounted on an axle of the motorcycle frame, perpendicularly to the longitudinal median plane of the motorcycle. This arrangement generally gives satisfactory performances and has revealed to be that ensuring the best steering of the front wheel, but the manufacture of the connecting arm has proved to be very expensive and there has become desirable, for reasons relates to space requirement, to shift the helical suspension spring with respect to the steering axis.